Another thought of a real cowboy song was that melodies were simple and often were to the "rhythm of the horse". That is when they weren't some high trottin' breakdown.

Another good source from folks that studied the actual early cowboy songs are my friends, the Bunkhouse Orchestra, AKA, the Deseret String Band as led by Hal Cannon. They have long since gone their separate ways but you can't go wrong with any of their recordings.